Calculus Examples

$f (x) = x \sqrt{4 - x^{2}}$

Step 1

Find the first derivative.

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Step 1.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{4 - x^{2}}$ as ${(4 - x^{2})}^{\frac{1}{2}}$ .

$f' (x) = \frac{d}{d x} (x {(4 - x^{2})}^{\frac{1}{2}})$

Step 1.2

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x$ and $g (x) = {(4 - x^{2})}^{\frac{1}{2}}$ .

$f' (x) = x \frac{d}{d x} ({(4 - x^{2})}^{\frac{1}{2}}) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{\frac{1}{2}}$ and $g (x) = 4 - x^{2}$ .

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Step 1.3.1

To apply the Chain Rule, set $u$ as $4 - x^{2}$ .

$f' (x) = x (\frac{d}{d u} (u^{\frac{1}{2}}) \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.3.2

Differentiate using the Power Rule which states that $\frac{d}{d u} [u^{n}]$ is $n u^{n - 1}$ where $n = \frac{1}{2}$ .

$f' (x) = x (\frac{1}{2} u^{\frac{1}{2} - 1} \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.3.3

Replace all occurrences of $u$ with $4 - x^{2}$ .

$f' (x) = x (\frac{1}{2} \cdot {(4 - x^{2})}^{\frac{1}{2} - 1} \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.4

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$f' (x) = x (\frac{1}{2} \cdot {(4 - x^{2})}^{\frac{1}{2} - 1 \cdot \frac{2}{2}} \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.5

Combine $- 1$ and $\frac{2}{2}$ .

$f' (x) = x (\frac{1}{2} \cdot {(4 - x^{2})}^{\frac{1}{2} + \frac{- 1 \cdot 2}{2}} \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.6

Combine the numerators over the common denominator.

$f' (x) = x (\frac{1}{2} \cdot {(4 - x^{2})}^{\frac{1 - 1 \cdot 2}{2}} \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.7

Simplify the numerator.

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Step 1.7.1

Multiply $- 1$ by $2$ .

$f' (x) = x (\frac{1}{2} \cdot {(4 - x^{2})}^{\frac{1 - 2}{2}} \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.7.2

Subtract $2$ from $1$ .

$f' (x) = x (\frac{1}{2} \cdot {(4 - x^{2})}^{\frac{- 1}{2}} \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.8

Combine fractions.

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Step 1.8.1

Move the negative in front of the fraction.

$f' (x) = x (\frac{1}{2} \cdot {(4 - x^{2})}^{- \frac{1}{2}} \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.8.2

Combine $\frac{1}{2}$ and ${(4 - x^{2})}^{- \frac{1}{2}}$ .

$f' (x) = x (\frac{{(4 - x^{2})}^{- \frac{1}{2}}}{2} \cdot \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.8.3

Move ${(4 - x^{2})}^{- \frac{1}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$f' (x) = x (\frac{1}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot \frac{d}{d x} (4 - x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.8.4

Combine $\frac{1}{2 {(4 - x^{2})}^{\frac{1}{2}}}$ and $x$ .

$f' (x) = \frac{x}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot \frac{d}{d x} (4 - x^{2}) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.9

By the Sum Rule, the derivative of $4 - x^{2}$ with respect to $x$ is $\frac{d}{d x} [4] + \frac{d}{d x} [- x^{2}]$ .

$f' (x) = \frac{x}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot (\frac{d}{d x} (4) + \frac{d}{d x} (- x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.10

Since $4$ is constant with respect to $x$ , the derivative of $4$ with respect to $x$ is $0$ .

$f' (x) = \frac{x}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot (0 + \frac{d}{d x} (- x^{2})) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.11

Add $0$ and $\frac{d}{d x} [- x^{2}]$ .

$f' (x) = \frac{x}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot \frac{d}{d x} (- x^{2}) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.12

Since $- 1$ is constant with respect to $x$ , the derivative of $- x^{2}$ with respect to $x$ is $- \frac{d}{d x} [x^{2}]$ .

$f' (x) = \frac{x}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot (- \frac{d}{d x} x^{2}) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.13

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$f' (x) = \frac{x}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot (- (2 x)) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.14

Combine fractions.

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Step 1.14.1

Multiply $2$ by $- 1$ .

$f' (x) = \frac{x}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot (- 2 x) + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.14.2

Combine $- 2$ and $\frac{x}{2 {(4 - x^{2})}^{\frac{1}{2}}}$ .

$f' (x) = \frac{- 2 x}{2 {(4 - x^{2})}^{\frac{1}{2}}} \cdot x + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.14.3

Combine $\frac{- 2 x}{2 {(4 - x^{2})}^{\frac{1}{2}}}$ and $x$ .

$f' (x) = \frac{- 2 x \cdot x}{2 {(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.15

Raise $x$ to the power of $1$ .

$f' (x) = \frac{- 2 (x \cdot x)}{2 {(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.16

Raise $x$ to the power of $1$ .

$f' (x) = \frac{- 2 (x \cdot x)}{2 {(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.17

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f' (x) = \frac{- 2 x^{1 + 1}}{2 {(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.18

Add $1$ and $1$ .

$f' (x) = \frac{- 2 x^{2}}{2 {(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.19

Factor $2$ out of $- 2 x^{2}$ .

$f' (x) = \frac{2 (- x^{2})}{2 {(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.20

Cancel the common factors.

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Step 1.20.1

Factor $2$ out of $2 {(4 - x^{2})}^{\frac{1}{2}}$ .

$f' (x) = \frac{2 (- x^{2})}{2 ({(4 - x^{2})}^{\frac{1}{2}})} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.20.2

Cancel the common factor.

$f' (x) = \frac{2 (- x^{2})}{2 {(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.20.3

Rewrite the expression.

$f' (x) = \frac{- x^{2}}{{(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.21

Move the negative in front of the fraction.

$f' (x) = - \frac{x^{2}}{{(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \frac{d}{d x} (x)$

Step 1.22

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$f' (x) = - \frac{x^{2}}{{(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}} \cdot 1$

Step 1.23

Multiply ${(4 - x^{2})}^{\frac{1}{2}}$ by $1$ .

$f' (x) = - \frac{x^{2}}{{(4 - x^{2})}^{\frac{1}{2}}} + {(4 - x^{2})}^{\frac{1}{2}}$

Step 1.24

To write ${(4 - x^{2})}^{\frac{1}{2}}$ as a fraction with a common denominator, multiply by $\frac{{(4 - x^{2})}^{\frac{1}{2}}}{{(4 - x^{2})}^{\frac{1}{2}}}$ .

$f' (x) = - \frac{x^{2}}{{(4 - x^{2})}^{\frac{1}{2}}} + \frac{{(4 - x^{2})}^{\frac{1}{2}} {(4 - x^{2})}^{\frac{1}{2}}}{{(4 - x^{2})}^{\frac{1}{2}}}$

Step 1.25

Combine the numerators over the common denominator.

$f' (x) = \frac{- x^{2} + {(4 - x^{2})}^{\frac{1}{2}} {(4 - x^{2})}^{\frac{1}{2}}}{{(4 - x^{2})}^{\frac{1}{2}}}$

Step 1.26

Multiply ${(4 - x^{2})}^{\frac{1}{2}}$ by ${(4 - x^{2})}^{\frac{1}{2}}$ by adding the exponents.

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Step 1.26.1

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f' (x) = \frac{- x^{2} + {(4 - x^{2})}^{\frac{1}{2} + \frac{1}{2}}}{{(4 - x^{2})}^{\frac{1}{2}}}$

Step 1.26.2

Combine the numerators over the common denominator.

$f' (x) = \frac{- x^{2} + {(4 - x^{2})}^{\frac{1 + 1}{2}}}{{(4 - x^{2})}^{\frac{1}{2}}}$

Step 1.26.3

Add $1$ and $1$ .

$f' (x) = \frac{- x^{2} + {(4 - x^{2})}^{\frac{2}{2}}}{{(4 - x^{2})}^{\frac{1}{2}}}$

Step 1.26.4

Divide $2$ by $2$ .

$f' (x) = \frac{- x^{2} + 4 - x^{2}}{{(4 - x^{2})}^{\frac{1}{2}}}$

Step 1.27

Simplify ${(4 - x^{2})}^{1}$ .

$f' (x) = \frac{- x^{2} + 4 - x^{2}}{{(4 - x^{2})}^{\frac{1}{2}}}$

Step 1.28

Subtract $x^{2}$ from $- x^{2}$ .

$f' (x) = \frac{- 2 x^{2} + 4}{{(4 - x^{2})}^{\frac{1}{2}}}$

Step 1.29

Reorder terms.

$f' (x) = \frac{- 2 x^{2} + 4}{{(- x^{2} + 4)}^{\frac{1}{2}}}$

Step 2

Find the second derivative.

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Step 2.1

Differentiate using the Quotient Rule which states that $\frac{d}{d x} [\frac{f (x)}{g (x)}]$ is $\frac{g (x) \frac{d}{d x} [f (x)] - f (x) \frac{d}{d x} [g (x)]}{{g (x)}^{2}}$ where $f (x) = - 2 x^{2} + 4$ and $g (x) = {(- x^{2} + 4)}^{\frac{1}{2}}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} \frac{d}{d x} (- 2 x^{2} + 4) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{{({(- x^{2} + 4)}^{\frac{1}{2}})}^{2}}$

Step 2.2

Multiply the exponents in ${({(- x^{2} + 4)}^{\frac{1}{2}})}^{2}$ .

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Step 2.2.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} \frac{d}{d x} (- 2 x^{2} + 4) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{{(- x^{2} + 4)}^{\frac{1}{2} \cdot 2}}$

Step 2.2.2

Cancel the common factor of $2$ .

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Step 2.2.2.1

Cancel the common factor.

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} \frac{d}{d x} (- 2 x^{2} + 4) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{{(- x^{2} + 4)}^{\frac{1}{2} \cdot 2}}$

Step 2.2.2.2

Rewrite the expression.

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} \frac{d}{d x} (- 2 x^{2} + 4) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{- x^{2} + 4}$

Step 2.3

Simplify.

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} \frac{d}{d x} (- 2 x^{2} + 4) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{- x^{2} + 4}$

Step 2.4

Differentiate.

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Step 2.4.1

By the Sum Rule, the derivative of $- 2 x^{2} + 4$ with respect to $x$ is $\frac{d}{d x} [- 2 x^{2}] + \frac{d}{d x} [4]$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (\frac{d}{d x} (- 2 x^{2}) + \frac{d}{d x} (4)) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{- x^{2} + 4}$

Step 2.4.2

Since $- 2$ is constant with respect to $x$ , the derivative of $- 2 x^{2}$ with respect to $x$ is $- 2 \frac{d}{d x} [x^{2}]$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 2 \frac{d}{d x} x^{2} + \frac{d}{d x} (4)) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{- x^{2} + 4}$

Step 2.4.3

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 2 (2 x) + \frac{d}{d x} (4)) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{- x^{2} + 4}$

Step 2.4.4

Multiply $2$ by $- 2$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x + \frac{d}{d x} (4)) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{- x^{2} + 4}$

Step 2.4.5

Since $4$ is constant with respect to $x$ , the derivative of $4$ with respect to $x$ is $0$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x + 0) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{- x^{2} + 4}$

Step 2.4.6

Add $- 4 x$ and $0$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{1}{2}}}{- x^{2} + 4}$

Step 2.5

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{\frac{1}{2}}$ and $g (x) = - x^{2} + 4$ .

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Step 2.5.1

To apply the Chain Rule, set $u$ as $- x^{2} + 4$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{d}{d u} (u^{\frac{1}{2}}) \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.5.2

Differentiate using the Power Rule which states that $\frac{d}{d u} [u^{n}]$ is $n u^{n - 1}$ where $n = \frac{1}{2}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2} u^{\frac{1}{2} - 1} \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.5.3

Replace all occurrences of $u$ with $- x^{2} + 4$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2} \cdot {(- x^{2} + 4)}^{\frac{1}{2} - 1} \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.6

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2} \cdot {(- x^{2} + 4)}^{\frac{1}{2} - 1 \cdot \frac{2}{2}} \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.7

Combine $- 1$ and $\frac{2}{2}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2} \cdot {(- x^{2} + 4)}^{\frac{1}{2} + \frac{- 1 \cdot 2}{2}} \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.8

Combine the numerators over the common denominator.

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2} \cdot {(- x^{2} + 4)}^{\frac{1 - 1 \cdot 2}{2}} \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.9

Simplify the numerator.

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Step 2.9.1

Multiply $- 1$ by $2$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2} \cdot {(- x^{2} + 4)}^{\frac{1 - 2}{2}} \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.9.2

Subtract $2$ from $1$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2} \cdot {(- x^{2} + 4)}^{\frac{- 1}{2}} \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.10

Combine fractions.

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Step 2.10.1

Move the negative in front of the fraction.

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2} \cdot {(- x^{2} + 4)}^{- \frac{1}{2}} \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.10.2

Combine $\frac{1}{2}$ and ${(- x^{2} + 4)}^{- \frac{1}{2}}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{{(- x^{2} + 4)}^{- \frac{1}{2}}}{2} \cdot \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.10.3

Move ${(- x^{2} + 4)}^{- \frac{1}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2 {(- x^{2} + 4)}^{\frac{1}{2}}} \cdot \frac{d}{d x} (- x^{2} + 4))}{- x^{2} + 4}$

Step 2.11

By the Sum Rule, the derivative of $- x^{2} + 4$ with respect to $x$ is $\frac{d}{d x} [- x^{2}] + \frac{d}{d x} [4]$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2 {(- x^{2} + 4)}^{\frac{1}{2}}} \cdot (\frac{d}{d x} (- x^{2}) + \frac{d}{d x} (4)))}{- x^{2} + 4}$

Step 2.12

Since $- 1$ is constant with respect to $x$ , the derivative of $- x^{2}$ with respect to $x$ is $- \frac{d}{d x} [x^{2}]$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2 {(- x^{2} + 4)}^{\frac{1}{2}}} \cdot (- \frac{d}{d x} x^{2} + \frac{d}{d x} (4)))}{- x^{2} + 4}$

Step 2.13

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2 {(- x^{2} + 4)}^{\frac{1}{2}}} \cdot (- (2 x) + \frac{d}{d x} (4)))}{- x^{2} + 4}$

Step 2.14

Multiply $2$ by $- 1$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2 {(- x^{2} + 4)}^{\frac{1}{2}}} \cdot (- 2 x + \frac{d}{d x} (4)))}{- x^{2} + 4}$

Step 2.15

Since $4$ is constant with respect to $x$ , the derivative of $4$ with respect to $x$ is $0$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2 {(- x^{2} + 4)}^{\frac{1}{2}}} \cdot (- 2 x + 0))}{- x^{2} + 4}$

Step 2.16

Simplify terms.

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Step 2.16.1

Add $- 2 x$ and $0$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{1}{2 {(- x^{2} + 4)}^{\frac{1}{2}}} \cdot (- 2 x))}{- x^{2} + 4}$

Step 2.16.2

Combine $- 2$ and $\frac{1}{2 {(- x^{2} + 4)}^{\frac{1}{2}}}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (\frac{- 2}{2 {(- x^{2} + 4)}^{\frac{1}{2}}} \cdot x)}{- x^{2} + 4}$

Step 2.16.3

Combine $\frac{- 2}{2 {(- x^{2} + 4)}^{\frac{1}{2}}}$ and $x$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) \frac{- 2 x}{2 {(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.16.4

Factor $2$ out of $- 2 x$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) \frac{2 (- x)}{2 {(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.17

Cancel the common factors.

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Step 2.17.1

Factor $2$ out of $2 {(- x^{2} + 4)}^{\frac{1}{2}}$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) \frac{2 (- x)}{2 ({(- x^{2} + 4)}^{\frac{1}{2}})}}{- x^{2} + 4}$

Step 2.17.2

Cancel the common factor.

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) \frac{2 (- x)}{2 {(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.17.3

Rewrite the expression.

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) \frac{- x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.18

Move the negative in front of the fraction.

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) - (- 2 x^{2} + 4) (- \frac{x}{{(- x^{2} + 4)}^{\frac{1}{2}}})}{- x^{2} + 4}$

Step 2.19

Multiply $- 1$ by $- 1$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) + 1 (- 2 x^{2} + 4) (\frac{x}{{(- x^{2} + 4)}^{\frac{1}{2}}})}{- x^{2} + 4}$

Step 2.20

Multiply $- 2 x^{2} + 4$ by $1$ .

$f'' (x) = \frac{{(- x^{2} + 4)}^{\frac{1}{2}} (- 4 x) + (- 2 x^{2} + 4) (\frac{x}{{(- x^{2} + 4)}^{\frac{1}{2}}})}{- x^{2} + 4}$

Step 2.21

Simplify.

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Step 2.21.1

Simplify the numerator.

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Step 2.21.1.1

Rewrite using the commutative property of multiplication.

$f'' (x) = \frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x + (- 2 x^{2} + 4) (\frac{x}{{(- x^{2} + 4)}^{\frac{1}{2}}})}{- x^{2} + 4}$

Step 2.21.1.2

Multiply $- 2 x^{2} + 4$ by $\frac{x}{{(- x^{2} + 4)}^{\frac{1}{2}}}$ .

$f'' (x) = \frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x + \frac{(- 2 x^{2} + 4) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.3

Factor $2$ out of $- 2 x^{2} + 4$ .

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Step 2.21.1.3.1

Factor $2$ out of $- 2 x^{2}$ .

$f'' (x) = \frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x + \frac{(2 (- x^{2}) + 4) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.3.2

Factor $2$ out of $4$ .

$f'' (x) = \frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x + \frac{(2 (- x^{2}) + 2 (2)) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.3.3

Factor $2$ out of $2 (- x^{2}) + 2 (2)$ .

$f'' (x) = \frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x + \frac{2 (- x^{2} + 2) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.4

To write $- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x$ as a fraction with a common denominator, multiply by $\frac{{(- x^{2} + 4)}^{\frac{1}{2}}}{{(- x^{2} + 4)}^{\frac{1}{2}}}$ .

$f'' (x) = \frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x \cdot \frac{{(- x^{2} + 4)}^{\frac{1}{2}}}{{(- x^{2} + 4)}^{\frac{1}{2}}} + \frac{2 (- x^{2} + 2) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.5

Combine $- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x$ and $\frac{{(- x^{2} + 4)}^{\frac{1}{2}}}{{(- x^{2} + 4)}^{\frac{1}{2}}}$ .

$f'' (x) = \frac{\frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x {(- x^{2} + 4)}^{\frac{1}{2}}}{{(- x^{2} + 4)}^{\frac{1}{2}}} + \frac{2 (- x^{2} + 2) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.6

Combine the numerators over the common denominator.

$f'' (x) = \frac{\frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x {(- x^{2} + 4)}^{\frac{1}{2}} + 2 (- x^{2} + 2) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7

Rewrite $\frac{- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x {(- x^{2} + 4)}^{\frac{1}{2}} + 2 (- x^{2} + 2) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}$ in a factored form.

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Step 2.21.1.7.1

Factor $2 x$ out of $- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x {(- x^{2} + 4)}^{\frac{1}{2}} + 2 (- x^{2} + 2) x$ .

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Step 2.21.1.7.1.1

Factor $2 x$ out of $- 4 {(- x^{2} + 4)}^{\frac{1}{2}} x {(- x^{2} + 4)}^{\frac{1}{2}}$ .

$f'' (x) = \frac{\frac{2 x (- 2 {(- x^{2} + 4)}^{\frac{1}{2}} {(- x^{2} + 4)}^{\frac{1}{2}}) + 2 (- x^{2} + 2) x}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7.1.2

Factor $2 x$ out of $2 (- x^{2} + 2) x$ .

$f'' (x) = \frac{\frac{2 x (- 2 {(- x^{2} + 4)}^{\frac{1}{2}} {(- x^{2} + 4)}^{\frac{1}{2}}) + 2 x (- x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7.1.3

Factor $2 x$ out of $2 x (- 2 {(- x^{2} + 4)}^{\frac{1}{2}} {(- x^{2} + 4)}^{\frac{1}{2}}) + 2 x (- x^{2} + 2)$ .

$f'' (x) = \frac{\frac{2 x (- 2 {(- x^{2} + 4)}^{\frac{1}{2}} {(- x^{2} + 4)}^{\frac{1}{2}} - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7.2

Combine exponents.

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Step 2.21.1.7.2.1

Multiply ${(- x^{2} + 4)}^{\frac{1}{2}}$ by ${(- x^{2} + 4)}^{\frac{1}{2}}$ by adding the exponents.

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Step 2.21.1.7.2.1.1

Move ${(- x^{2} + 4)}^{\frac{1}{2}}$ .

$f'' (x) = \frac{\frac{2 x (- 2 ({(- x^{2} + 4)}^{\frac{1}{2}} {(- x^{2} + 4)}^{\frac{1}{2}}) - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7.2.1.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f'' (x) = \frac{\frac{2 x (- 2 {(- x^{2} + 4)}^{\frac{1}{2} + \frac{1}{2}} - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7.2.1.3

Combine the numerators over the common denominator.

$f'' (x) = \frac{\frac{2 x (- 2 {(- x^{2} + 4)}^{\frac{1 + 1}{2}} - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7.2.1.4

Add $1$ and $1$ .

$f'' (x) = \frac{\frac{2 x (- 2 {(- x^{2} + 4)}^{\frac{2}{2}} - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7.2.1.5

Divide $2$ by $2$ .

$f'' (x) = \frac{\frac{2 x (- 2 (- x^{2} + 4) - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.7.2.2

Simplify $- 2 {(- x^{2} + 4)}^{1}$ .

$f'' (x) = \frac{\frac{2 x (- 2 (- x^{2} + 4) - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.8

Simplify the numerator.

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Step 2.21.1.8.1

Apply the distributive property.

$f'' (x) = \frac{\frac{2 x (- 2 (- x^{2}) - 2 \cdot 4 - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.8.2

Multiply $- 1$ by $- 2$ .

$f'' (x) = \frac{\frac{2 x (2 x^{2} - 2 \cdot 4 - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.8.3

Multiply $- 2$ by $4$ .

$f'' (x) = \frac{\frac{2 x (2 x^{2} - 8 - x^{2} + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.8.4

Subtract $x^{2}$ from $2 x^{2}$ .

$f'' (x) = \frac{\frac{2 x (x^{2} - 8 + 2)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.1.8.5

Add $- 8$ and $2$ .

$f'' (x) = \frac{\frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$

Step 2.21.2

Combine terms.

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Step 2.21.2.1

Rewrite $\frac{\frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1}{2}}}}{- x^{2} + 4}$ as a product.

$f'' (x) = \frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1}{2}}} \cdot \frac{1}{- x^{2} + 4}$

Step 2.21.2.2

Multiply $\frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1}{2}}}$ by $\frac{1}{- x^{2} + 4}$ .

$f'' (x) = \frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1}{2}} (- x^{2} + 4)}$

Step 2.21.2.3

Multiply ${(- x^{2} + 4)}^{\frac{1}{2}}$ by $- x^{2} + 4$ by adding the exponents.

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Step 2.21.2.3.1

Multiply ${(- x^{2} + 4)}^{\frac{1}{2}}$ by $- x^{2} + 4$ .

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Step 2.21.2.3.1.1

Raise $- x^{2} + 4$ to the power of $1$ .

$f'' (x) = \frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1}{2}} (- x^{2} + 4)}$

Step 2.21.2.3.1.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f'' (x) = \frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1}{2} + 1}}$

Step 2.21.2.3.2

Write $1$ as a fraction with a common denominator.

$f'' (x) = \frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1}{2} + \frac{2}{2}}}$

Step 2.21.2.3.3

Combine the numerators over the common denominator.

$f'' (x) = \frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{1 + 2}{2}}}$

Step 2.21.2.3.4

Add $1$ and $2$ .

$f'' (x) = \frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{3}{2}}}$

Step 3

Find the third derivative.

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Step 3.1

Since $2$ is constant with respect to $x$ , the derivative of $\frac{2 x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{3}{2}}}$ with respect to $x$ is $2 \frac{d}{d x} [\frac{x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{3}{2}}}]$ .

$f''' (x) = 2 \frac{d}{d x} (\frac{x (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{3}{2}}})$

Step 3.2

Differentiate using the Quotient Rule which states that $\frac{d}{d x} [\frac{f (x)}{g (x)}]$ is $\frac{g (x) \frac{d}{d x} [f (x)] - f (x) \frac{d}{d x} [g (x)]}{{g (x)}^{2}}$ where $f (x) = x (x^{2} - 6)$ and $g (x) = {(- x^{2} + 4)}^{\frac{3}{2}}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} \frac{d}{d x} (x (x^{2} - 6)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{({(- x^{2} + 4)}^{\frac{3}{2}})}^{2}})$

Step 3.3

Multiply the exponents in ${({(- x^{2} + 4)}^{\frac{3}{2}})}^{2}$ .

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Step 3.3.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} \frac{d}{d x} (x (x^{2} - 6)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{\frac{3}{2} \cdot 2}})$

Step 3.3.2

Cancel the common factor of $2$ .

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Step 3.3.2.1

Cancel the common factor.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} \frac{d}{d x} (x (x^{2} - 6)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{\frac{3}{2} \cdot 2}})$

Step 3.3.2.2

Rewrite the expression.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} \frac{d}{d x} (x (x^{2} - 6)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.4

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x$ and $g (x) = x^{2} - 6$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (x \frac{d}{d x} (x^{2} - 6) + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.5

Differentiate.

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Step 3.5.1

By the Sum Rule, the derivative of $x^{2} - 6$ with respect to $x$ is $\frac{d}{d x} [x^{2}] + \frac{d}{d x} [- 6]$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (x (\frac{d}{d x} (x^{2}) + \frac{d}{d x} (- 6)) + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.5.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (x (2 x + \frac{d}{d x} (- 6)) + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.5.3

Since $- 6$ is constant with respect to $x$ , the derivative of $- 6$ with respect to $x$ is $0$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (x (2 x + 0) + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.5.4

Add $2 x$ and $0$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (x (2 x) + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.6

Raise $x$ to the power of $1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (2 (x \cdot x) + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.7

Raise $x$ to the power of $1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (2 (x \cdot x) + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.8

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (2 x^{1 + 1} + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.9

Differentiate using the Power Rule.

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Step 3.9.1

Add $1$ and $1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (2 x^{2} + (x^{2} - 6) \frac{d}{d x} (x)) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.9.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (2 x^{2} + (x^{2} - 6) \cdot 1) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.9.3

Simplify by adding terms.

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Step 3.9.3.1

Multiply $x^{2} - 6$ by $1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (2 x^{2} + x^{2} - 6) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.9.3.2

Add $2 x^{2}$ and $x^{2}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) \frac{d}{d x} {(- x^{2} + 4)}^{\frac{3}{2}}}{{(- x^{2} + 4)}^{3}})$

Step 3.10

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{\frac{3}{2}}$ and $g (x) = - x^{2} + 4$ .

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Step 3.10.1

To apply the Chain Rule, set $u$ as $- x^{2} + 4$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{d}{d u} (u^{\frac{3}{2}}) \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.10.2

Differentiate using the Power Rule which states that $\frac{d}{d u} [u^{n}]$ is $n u^{n - 1}$ where $n = \frac{3}{2}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{3}{2} u^{\frac{3}{2} - 1} \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.10.3

Replace all occurrences of $u$ with $- x^{2} + 4$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{3}{2} \cdot {(- x^{2} + 4)}^{\frac{3}{2} - 1} \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.11

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{3}{2} \cdot {(- x^{2} + 4)}^{\frac{3}{2} - 1 \cdot \frac{2}{2}} \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.12

Combine $- 1$ and $\frac{2}{2}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{3}{2} \cdot {(- x^{2} + 4)}^{\frac{3}{2} + \frac{- 1 \cdot 2}{2}} \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.13

Combine the numerators over the common denominator.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{3}{2} \cdot {(- x^{2} + 4)}^{\frac{3 - 1 \cdot 2}{2}} \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.14

Simplify the numerator.

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Step 3.14.1

Multiply $- 1$ by $2$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{3}{2} \cdot {(- x^{2} + 4)}^{\frac{3 - 2}{2}} \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.14.2

Subtract $2$ from $3$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{3}{2} \cdot {(- x^{2} + 4)}^{\frac{1}{2}} \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.15

Combine fractions.

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Step 3.15.1

Combine $\frac{3}{2}$ and ${(- x^{2} + 4)}^{\frac{1}{2}}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - x (x^{2} - 6) (\frac{3 {(- x^{2} + 4)}^{\frac{1}{2}}}{2} \cdot \frac{d}{d x} (- x^{2} + 4))}{{(- x^{2} + 4)}^{3}})$

Step 3.15.2

Combine $\frac{3 {(- x^{2} + 4)}^{\frac{1}{2}}}{2}$ and $x$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - \frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2} \cdot (x^{2} - 6) \frac{d}{d x} (- x^{2} + 4)}{{(- x^{2} + 4)}^{3}})$

Step 3.16

By the Sum Rule, the derivative of $- x^{2} + 4$ with respect to $x$ is $\frac{d}{d x} [- x^{2}] + \frac{d}{d x} [4]$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - \frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2} \cdot ((x^{2} - 6) (\frac{d}{d x} (- x^{2}) + \frac{d}{d x} (4)))}{{(- x^{2} + 4)}^{3}})$

Step 3.17

Since $- 1$ is constant with respect to $x$ , the derivative of $- x^{2}$ with respect to $x$ is $- \frac{d}{d x} [x^{2}]$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - \frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2} \cdot ((x^{2} - 6) (- \frac{d}{d x} x^{2} + \frac{d}{d x} (4)))}{{(- x^{2} + 4)}^{3}})$

Step 3.18

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - \frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2} \cdot ((x^{2} - 6) (- (2 x) + \frac{d}{d x} (4)))}{{(- x^{2} + 4)}^{3}})$

Step 3.19

Multiply $2$ by $- 1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - \frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2} \cdot ((x^{2} - 6) (- 2 x + \frac{d}{d x} (4)))}{{(- x^{2} + 4)}^{3}})$

Step 3.20

Since $4$ is constant with respect to $x$ , the derivative of $4$ with respect to $x$ is $0$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - \frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2} \cdot ((x^{2} - 6) (- 2 x + 0))}{{(- x^{2} + 4)}^{3}})$

Step 3.21

Combine fractions.

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Step 3.21.1

Add $- 2 x$ and $0$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) - \frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2} \cdot ((x^{2} - 6) (- 2 x))}{{(- x^{2} + 4)}^{3}})$

Step 3.21.2

Multiply $- 2$ by $- 1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + 2 (\frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2}) \cdot ((x^{2} - 6) x)}{{(- x^{2} + 4)}^{3}})$

Step 3.21.3

Combine $2$ and $\frac{3 {(- x^{2} + 4)}^{\frac{1}{2}} x}{2}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{2 (3 {(- x^{2} + 4)}^{\frac{1}{2}} x)}{2} \cdot ((x^{2} - 6) x)}{{(- x^{2} + 4)}^{3}})$

Step 3.21.4

Multiply $3$ by $2$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{6 ({(- x^{2} + 4)}^{\frac{1}{2}} x)}{2} \cdot ((x^{2} - 6) x)}{{(- x^{2} + 4)}^{3}})$

Step 3.21.5

Combine $x$ and $\frac{6 ({(- x^{2} + 4)}^{\frac{1}{2}} x)}{2}$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{x (6 ({(- x^{2} + 4)}^{\frac{1}{2}} x))}{2} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.22

Raise $x$ to the power of $1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{x \cdot x (6 ({(- x^{2} + 4)}^{\frac{1}{2}}))}{2} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.23

Raise $x$ to the power of $1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{x \cdot x (6 ({(- x^{2} + 4)}^{\frac{1}{2}}))}{2} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.24

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{x^{1 + 1} (6 ({(- x^{2} + 4)}^{\frac{1}{2}}))}{2} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.25

Add $1$ and $1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{x^{2} (6 ({(- x^{2} + 4)}^{\frac{1}{2}}))}{2} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.26

Factor $2$ out of $x^{2} (6 {(- x^{2} + 4)}^{\frac{1}{2}})$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{2 (x^{2} (3 {(- x^{2} + 4)}^{\frac{1}{2}}))}{2} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.27

Cancel the common factors.

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Step 3.27.1

Factor $2$ out of $2$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{2 (x^{2} (3 {(- x^{2} + 4)}^{\frac{1}{2}}))}{2 (1)} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.27.2

Cancel the common factor.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{2 (x^{2} (3 {(- x^{2} + 4)}^{\frac{1}{2}}))}{2 \cdot 1} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.27.3

Rewrite the expression.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + \frac{x^{2} (3 {(- x^{2} + 4)}^{\frac{1}{2}})}{1} \cdot (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.27.4

Divide $x^{2} (3 {(- x^{2} + 4)}^{\frac{1}{2}})$ by $1$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + x^{2} (3 {(- x^{2} + 4)}^{\frac{1}{2}}) (x^{2} - 6)}{{(- x^{2} + 4)}^{3}})$

Step 3.28

Factor ${(- x^{2} + 4)}^{\frac{1}{2}}$ out of ${(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + x^{2} (3 {(- x^{2} + 4)}^{\frac{1}{2}}) (x^{2} - 6)$ .

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Step 3.28.1

Reorder $x^{2}$ and $3$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6) + 3 \cdot (x^{2} {(- x^{2} + 4)}^{\frac{1}{2}} (x^{2} - 6))}{{(- x^{2} + 4)}^{3}})$

Step 3.28.2

Factor ${(- x^{2} + 4)}^{\frac{1}{2}}$ out of ${(- x^{2} + 4)}^{\frac{3}{2}} (3 x^{2} - 6)$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{1}{2}} ({(- x^{2} + 4)}^{\frac{2}{2}} (3 x^{2} - 6)) + 3 \cdot (x^{2} {(- x^{2} + 4)}^{\frac{1}{2}} (x^{2} - 6))}{{(- x^{2} + 4)}^{3}})$

Step 3.28.3

Factor ${(- x^{2} + 4)}^{\frac{1}{2}}$ out of $3 \cdot x^{2} {(- x^{2} + 4)}^{\frac{1}{2}} (x^{2} - 6)$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{1}{2}} ({(- x^{2} + 4)}^{\frac{2}{2}} (3 x^{2} - 6)) + {(- x^{2} + 4)}^{\frac{1}{2}} (3 \cdot (x^{2} (x^{2} - 6)))}{{(- x^{2} + 4)}^{3}})$

Step 3.28.4

Factor ${(- x^{2} + 4)}^{\frac{1}{2}}$ out of ${(- x^{2} + 4)}^{\frac{1}{2}} ({(- x^{2} + 4)}^{\frac{2}{2}} (3 x^{2} - 6)) + {(- x^{2} + 4)}^{\frac{1}{2}} (3 \cdot x^{2} (x^{2} - 6))$ .

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{1}{2}} ({(- x^{2} + 4)}^{\frac{2}{2}} (3 x^{2} - 6) + 3 \cdot (x^{2} (x^{2} - 6)))}{{(- x^{2} + 4)}^{3}})$

Step 3.29

Cancel the common factor of $2$ .

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Step 3.29.1

Cancel the common factor.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{1}{2}} ({(- x^{2} + 4)}^{\frac{2}{2}} (3 x^{2} - 6) + 3 \cdot (x^{2} (x^{2} - 6)))}{{(- x^{2} + 4)}^{3}})$

Step 3.29.2

Rewrite the expression.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{1}{2}} ((- x^{2} + 4) (3 x^{2} - 6) + 3 \cdot (x^{2} (x^{2} - 6)))}{{(- x^{2} + 4)}^{3}})$

Step 3.30

Simplify.

$f''' (x) = 2 (\frac{{(- x^{2} + 4)}^{\frac{1}{2}} ((- x^{2} + 4) (3 x^{2} - 6) + 3 \cdot (x^{2} (x^{2} - 6)))}{{(- x^{2} + 4)}^{3}})$

Step 3.31

Move ${(- x^{2} + 4)}^{\frac{1}{2}}$ to the denominator using the negative exponent rule $b^{n} = \frac{1}{b^{- n}}$ .

$f''' (x) = 2 (\frac{(- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6)}{{(- x^{2} + 4)}^{3} {(- x^{2} + 4)}^{- \frac{1}{2}}})$

Step 3.32

Multiply ${(- x^{2} + 4)}^{3}$ by ${(- x^{2} + 4)}^{- \frac{1}{2}}$ by adding the exponents.

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Step 3.32.1

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f''' (x) = 2 (\frac{(- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6)}{{(- x^{2} + 4)}^{3 - \frac{1}{2}}})$

Step 3.32.2

To write $3$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$f''' (x) = 2 (\frac{(- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6)}{{(- x^{2} + 4)}^{3 \cdot \frac{2}{2} - \frac{1}{2}}})$

Step 3.32.3

Combine $3$ and $\frac{2}{2}$ .

$f''' (x) = 2 (\frac{(- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{3 \cdot 2}{2} - \frac{1}{2}}})$

Step 3.32.4

Combine the numerators over the common denominator.

$f''' (x) = 2 (\frac{(- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{3 \cdot 2 - 1}{2}}})$

Step 3.32.5

Simplify the numerator.

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Step 3.32.5.1

Multiply $3$ by $2$ .

$f''' (x) = 2 (\frac{(- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{6 - 1}{2}}})$

Step 3.32.5.2

Subtract $1$ from $6$ .

$f''' (x) = 2 (\frac{(- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}})$

Step 3.33

Combine $2$ and $\frac{(- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$ .

$f''' (x) = \frac{2 ((- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} (x^{2} - 6))}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34

Simplify.

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Step 3.34.1

Apply the distributive property.

$f''' (x) = \frac{2 ((- x^{2} + 4) (3 x^{2} - 6) + 3 x^{2} x^{2} + 3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.2

Apply the distributive property.

$f''' (x) = \frac{2 ((- x^{2} + 4) (3 x^{2} - 6)) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3

Simplify the numerator.

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Step 3.34.3.1

Simplify each term.

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Step 3.34.3.1.1

Expand $(- x^{2} + 4) (3 x^{2} - 6)$ using the FOIL Method.

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Step 3.34.3.1.1.1

Apply the distributive property.

$f''' (x) = \frac{2 (- x^{2} (3 x^{2} - 6) + 4 (3 x^{2} - 6)) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.1.2

Apply the distributive property.

$f''' (x) = \frac{2 (- x^{2} (3 x^{2}) - x^{2} \cdot - 6 + 4 (3 x^{2} - 6)) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.1.3

Apply the distributive property.

$f''' (x) = \frac{2 (- x^{2} (3 x^{2}) - x^{2} \cdot - 6 + 4 (3 x^{2}) + 4 \cdot - 6) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2

Simplify and combine like terms.

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Step 3.34.3.1.2.1

Simplify each term.

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Step 3.34.3.1.2.1.1

Rewrite using the commutative property of multiplication.

$f''' (x) = \frac{2 (- 1 \cdot (3 x^{2} x^{2}) - x^{2} \cdot - 6 + 4 (3 x^{2}) + 4 \cdot - 6) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2.1.2

Multiply $x^{2}$ by $x^{2}$ by adding the exponents.

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Step 3.34.3.1.2.1.2.1

Move $x^{2}$ .

$f''' (x) = \frac{2 (- 1 \cdot (3 (x^{2} x^{2})) - x^{2} \cdot - 6 + 4 (3 x^{2}) + 4 \cdot - 6) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2.1.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f''' (x) = \frac{2 (- 1 \cdot (3 x^{2 + 2}) - x^{2} \cdot - 6 + 4 (3 x^{2}) + 4 \cdot - 6) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2.1.2.3

Add $2$ and $2$ .

$f''' (x) = \frac{2 (- 1 \cdot (3 x^{4}) - x^{2} \cdot - 6 + 4 (3 x^{2}) + 4 \cdot - 6) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2.1.3

Multiply $- 1$ by $3$ .

$f''' (x) = \frac{2 (- 3 x^{4} - x^{2} \cdot - 6 + 4 (3 x^{2}) + 4 \cdot - 6) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2.1.4

Multiply $- 6$ by $- 1$ .

$f''' (x) = \frac{2 (- 3 x^{4} + 6 x^{2} + 4 (3 x^{2}) + 4 \cdot - 6) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2.1.5

Multiply $3$ by $4$ .

$f''' (x) = \frac{2 (- 3 x^{4} + 6 x^{2} + 12 x^{2} + 4 \cdot - 6) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2.1.6

Multiply $4$ by $- 6$ .

$f''' (x) = \frac{2 (- 3 x^{4} + 6 x^{2} + 12 x^{2} - 24) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.2.2

Add $6 x^{2}$ and $12 x^{2}$ .

$f''' (x) = \frac{2 (- 3 x^{4} + 18 x^{2} - 24) + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.3

Apply the distributive property.

$f''' (x) = \frac{2 (- 3 x^{4}) + 2 (18 x^{2}) + 2 \cdot - 24 + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.4

Simplify.

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Step 3.34.3.1.4.1

Multiply $- 3$ by $2$ .

$f''' (x) = \frac{- 6 x^{4} + 2 (18 x^{2}) + 2 \cdot - 24 + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.4.2

Multiply $18$ by $2$ .

$f''' (x) = \frac{- 6 x^{4} + 36 x^{2} + 2 \cdot - 24 + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.4.3

Multiply $2$ by $- 24$ .

$f''' (x) = \frac{- 6 x^{4} + 36 x^{2} - 48 + 2 (3 x^{2} x^{2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.5

Multiply $x^{2}$ by $x^{2}$ by adding the exponents.

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Step 3.34.3.1.5.1

Move $x^{2}$ .

$f''' (x) = \frac{- 6 x^{4} + 36 x^{2} - 48 + 2 (3 (x^{2} x^{2})) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.5.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$f''' (x) = \frac{- 6 x^{4} + 36 x^{2} - 48 + 2 (3 x^{2 + 2}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.5.3

Add $2$ and $2$ .

$f''' (x) = \frac{- 6 x^{4} + 36 x^{2} - 48 + 2 (3 x^{4}) + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.6

Multiply $3$ by $2$ .

$f''' (x) = \frac{- 6 x^{4} + 36 x^{2} - 48 + 6 x^{4} + 2 (3 x^{2} \cdot - 6)}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.7

Multiply $- 6$ by $3$ .

$f''' (x) = \frac{- 6 x^{4} + 36 x^{2} - 48 + 6 x^{4} + 2 (- 18 x^{2})}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.1.8

Multiply $- 18$ by $2$ .

$f''' (x) = \frac{- 6 x^{4} + 36 x^{2} - 48 + 6 x^{4} - 36 x^{2}}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.2

Combine the opposite terms in $- 6 x^{4} + 36 x^{2} - 48 + 6 x^{4} - 36 x^{2}$ .

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Step 3.34.3.2.1

Add $- 6 x^{4}$ and $6 x^{4}$ .

$f''' (x) = \frac{36 x^{2} - 48 + 0 - 36 x^{2}}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.2.2

Add $36 x^{2} - 48$ and $0$ .

$f''' (x) = \frac{36 x^{2} - 48 - 36 x^{2}}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.2.3

Subtract $36 x^{2}$ from $36 x^{2}$ .

$f''' (x) = \frac{0 - 48}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.3.2.4

Subtract $48$ from $0$ .

$f''' (x) = \frac{- 48}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 3.34.4

Move the negative in front of the fraction.

$f''' (x) = - \frac{48}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 4

Find the fourth derivative.

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Step 4.1

Differentiate using the Constant Multiple Rule.

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Step 4.1.1

Since $- 48$ is constant with respect to $x$ , the derivative of $- \frac{48}{{(- x^{2} + 4)}^{\frac{5}{2}}}$ with respect to $x$ is $- 48 \frac{d}{d x} [\frac{1}{{(- x^{2} + 4)}^{\frac{5}{2}}}]$ .

$f^{4} (x) = - 48 \frac{d}{d x} \frac{1}{{(- x^{2} + 4)}^{\frac{5}{2}}}$

Step 4.1.2

Apply basic rules of exponents.

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Step 4.1.2.1

Rewrite $\frac{1}{{(- x^{2} + 4)}^{\frac{5}{2}}}$ as ${({(- x^{2} + 4)}^{\frac{5}{2}})}^{- 1}$ .

$f^{4} (x) = - 48 \frac{d}{d x} {({(- x^{2} + 4)}^{\frac{5}{2}})}^{- 1}$

Step 4.1.2.2

Multiply the exponents in ${({(- x^{2} + 4)}^{\frac{5}{2}})}^{- 1}$ .

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Step 4.1.2.2.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$f^{4} (x) = - 48 \frac{d}{d x} {(- x^{2} + 4)}^{\frac{5}{2} \cdot - 1}$

Step 4.1.2.2.2

Multiply $\frac{5}{2} \cdot - 1$ .

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Step 4.1.2.2.2.1

Combine $\frac{5}{2}$ and $- 1$ .

$f^{4} (x) = - 48 \frac{d}{d x} {(- x^{2} + 4)}^{\frac{5 \cdot - 1}{2}}$

Step 4.1.2.2.2.2

Multiply $5$ by $- 1$ .

$f^{4} (x) = - 48 \frac{d}{d x} {(- x^{2} + 4)}^{\frac{- 5}{2}}$

Step 4.1.2.2.3

Move the negative in front of the fraction.

$f^{4} (x) = - 48 \frac{d}{d x} {(- x^{2} + 4)}^{- \frac{5}{2}}$

Step 4.2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{- \frac{5}{2}}$ and $g (x) = - x^{2} + 4$ .

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Step 4.2.1

To apply the Chain Rule, set $u$ as $- x^{2} + 4$ .

$f^{4} (x) = - 48 (\frac{d}{d u} (u^{- \frac{5}{2}}) \frac{d}{d x} (- x^{2} + 4))$

Step 4.2.2

Differentiate using the Power Rule which states that $\frac{d}{d u} [u^{n}]$ is $n u^{n - 1}$ where $n = - \frac{5}{2}$ .

$f^{4} (x) = - 48 (- \frac{5}{2} u^{- \frac{5}{2} - 1} \frac{d}{d x} (- x^{2} + 4))$

Step 4.2.3

Replace all occurrences of $u$ with $- x^{2} + 4$ .

$f^{4} (x) = - 48 (- \frac{5}{2} \cdot {(- x^{2} + 4)}^{- \frac{5}{2} - 1} \frac{d}{d x} (- x^{2} + 4))$

Step 4.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$f^{4} (x) = - 48 (- \frac{5}{2} \cdot {(- x^{2} + 4)}^{- \frac{5}{2} - 1 \cdot \frac{2}{2}} \frac{d}{d x} (- x^{2} + 4))$

Step 4.4

Combine $- 1$ and $\frac{2}{2}$ .

$f^{4} (x) = - 48 (- \frac{5}{2} \cdot {(- x^{2} + 4)}^{- \frac{5}{2} + \frac{- 1 \cdot 2}{2}} \frac{d}{d x} (- x^{2} + 4))$

Step 4.5

Combine the numerators over the common denominator.

$f^{4} (x) = - 48 (- \frac{5}{2} \cdot {(- x^{2} + 4)}^{\frac{- 5 - 1 \cdot 2}{2}} \frac{d}{d x} (- x^{2} + 4))$

Step 4.6

Simplify the numerator.

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Step 4.6.1

Multiply $- 1$ by $2$ .

$f^{4} (x) = - 48 (- \frac{5}{2} \cdot {(- x^{2} + 4)}^{\frac{- 5 - 2}{2}} \frac{d}{d x} (- x^{2} + 4))$

Step 4.6.2

Subtract $2$ from $- 5$ .

$f^{4} (x) = - 48 (- \frac{5}{2} \cdot {(- x^{2} + 4)}^{\frac{- 7}{2}} \frac{d}{d x} (- x^{2} + 4))$

Step 4.7

Move the negative in front of the fraction.

$f^{4} (x) = - 48 (- \frac{5}{2} \cdot {(- x^{2} + 4)}^{- \frac{7}{2}} \frac{d}{d x} (- x^{2} + 4))$

Step 4.8

Combine ${(- x^{2} + 4)}^{- \frac{7}{2}}$ and $\frac{5}{2}$ .

$f^{4} (x) = - 48 (- \frac{{(- x^{2} + 4)}^{- \frac{7}{2}} \cdot 5}{2} \cdot \frac{d}{d x} (- x^{2} + 4))$

Step 4.9

Simplify the expression.

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Step 4.9.1

Move $5$ to the left of ${(- x^{2} + 4)}^{- \frac{7}{2}}$ .

$f^{4} (x) = - 48 (- \frac{5 \cdot {(- x^{2} + 4)}^{- \frac{7}{2}}}{2} \cdot \frac{d}{d x} (- x^{2} + 4))$

Step 4.9.2

Move ${(- x^{2} + 4)}^{- \frac{7}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$f^{4} (x) = - 48 (- \frac{5}{2 {(- x^{2} + 4)}^{\frac{7}{2}}} \cdot \frac{d}{d x} (- x^{2} + 4))$

Step 4.9.3

Multiply $- 1$ by $- 48$ .

$f^{4} (x) = 48 (\frac{5}{2 {(- x^{2} + 4)}^{\frac{7}{2}}} \cdot \frac{d}{d x} (- x^{2} + 4))$

Step 4.10

Combine $\frac{5}{2 {(- x^{2} + 4)}^{\frac{7}{2}}}$ and $48$ .

$f^{4} (x) = \frac{5 \cdot 48}{2 {(- x^{2} + 4)}^{\frac{7}{2}}} \cdot \frac{d}{d x} (- x^{2} + 4)$

Step 4.11

Multiply $5$ by $48$ .

$f^{4} (x) = \frac{240}{2 {(- x^{2} + 4)}^{\frac{7}{2}}} \cdot \frac{d}{d x} (- x^{2} + 4)$

Step 4.12

Factor $2$ out of $240$ .

$f^{4} (x) = \frac{2 \cdot 120}{2 {(- x^{2} + 4)}^{\frac{7}{2}}} \cdot \frac{d}{d x} (- x^{2} + 4)$

Step 4.13

Cancel the common factors.

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Step 4.13.1

Factor $2$ out of $2 {(- x^{2} + 4)}^{\frac{7}{2}}$ .

$f^{4} (x) = \frac{2 \cdot 120}{2 ({(- x^{2} + 4)}^{\frac{7}{2}})} \cdot \frac{d}{d x} (- x^{2} + 4)$

Step 4.13.2

Cancel the common factor.

$f^{4} (x) = \frac{2 \cdot 120}{2 {(- x^{2} + 4)}^{\frac{7}{2}}} \cdot \frac{d}{d x} (- x^{2} + 4)$

Step 4.13.3

Rewrite the expression.

$f^{4} (x) = \frac{120}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot \frac{d}{d x} (- x^{2} + 4)$

Step 4.14

By the Sum Rule, the derivative of $- x^{2} + 4$ with respect to $x$ is $\frac{d}{d x} [- x^{2}] + \frac{d}{d x} [4]$ .

$f^{4} (x) = \frac{120}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot (\frac{d}{d x} (- x^{2}) + \frac{d}{d x} (4))$

Step 4.15

Since $- 1$ is constant with respect to $x$ , the derivative of $- x^{2}$ with respect to $x$ is $- \frac{d}{d x} [x^{2}]$ .

$f^{4} (x) = \frac{120}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot (- \frac{d}{d x} x^{2} + \frac{d}{d x} (4))$

Step 4.16

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$f^{4} (x) = \frac{120}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot (- (2 x) + \frac{d}{d x} (4))$

Step 4.17

Multiply $2$ by $- 1$ .

$f^{4} (x) = \frac{120}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot (- 2 x + \frac{d}{d x} (4))$

Step 4.18

Since $4$ is constant with respect to $x$ , the derivative of $4$ with respect to $x$ is $0$ .

$f^{4} (x) = \frac{120}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot (- 2 x + 0)$

Step 4.19

Combine fractions.

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Step 4.19.1

Add $- 2 x$ and $0$ .

$f^{4} (x) = \frac{120}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot (- 2 x)$

Step 4.19.2

Combine $- 2$ and $\frac{120}{{(- x^{2} + 4)}^{\frac{7}{2}}}$ .

$f^{4} (x) = \frac{- 2 \cdot 120}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot x$

Step 4.19.3

Multiply $- 2$ by $120$ .

$f^{4} (x) = \frac{- 240}{{(- x^{2} + 4)}^{\frac{7}{2}}} \cdot x$

Step 4.19.4

Combine $\frac{- 240}{{(- x^{2} + 4)}^{\frac{7}{2}}}$ and $x$ .

$f^{4} (x) = \frac{- 240 x}{{(- x^{2} + 4)}^{\frac{7}{2}}}$

Step 4.19.5

Move the negative in front of the fraction.

$f^{4} (x) = - \frac{240 x}{{(- x^{2} + 4)}^{\frac{7}{2}}}$

Step 5

The fourth derivative of $f (x)$ with respect to $x$ is $- \frac{240 x}{{(- x^{2} + 4)}^{\frac{7}{2}}}$ .

$- \frac{240 x}{{(- x^{2} + 4)}^{\frac{7}{2}}}$